Constant velocity joints (CVJ) connecting shafts to drive units are common components in automotive vehicles. The drive unit typically has an output shaft or an input shaft for receiving the joint. Typically, the drive unit is an axle, transfer case, transmission, power take-off unit or other torque device, all of which are common components in automotive vehicles. Typically, one or more joints are assembled to the shaft to form a propeller or drive shaft assembly. It is the propeller shaft assembly which is connected, for instance, at one end to an output shaft of a transmission and, at the other end, to an input shaft of a differential. The shaft is solid or tubular with ends adapted to attach the shaft to an inner race of the joint thereby allowing an outer race connection to a drive unit. The inner race of the joint is typically press-fit, splined, or pinned to the shaft making the outer race of the joint available to be bolted or press-fit to a hub connector, flange or stubshaft of the particular drive unit. At the other end of the propeller shaft, the same typical or traditional connection is made to a second drive unit when connecting the shaft between the two drive units. Connecting the shaft to a drive unit via the constant velocity joint in this manner is considered a traditional connection. A Direct Torque Flow (DTF) connection is a newer connection style that has advantages and improvements over a traditional connection. The constant velocity joint, whether in a traditional or DTF connection, requires the internal cavity to be sealed from the external environment in which it is utilized, for example by an internal radial diaphragm (IRD) boot or convoluted boot assembly.
The internal radial diaphragm (IRD) boot or J-boot provides a seal to prevent joint contamination or lubricant leakage. The IRD boot requires a first end of the boot to be crimped upon a cover that extends away from an outer joint part. The crimped connection may lead to leaks or other contamination of the joint due to an inadequate seal between the first end of the boot and the cover. Moreover, the internal joint may be compromised should the cover fail or the cover connection become compromised where it attaches to the outer joint part. In operation, the IRD boot is also sensitive to increased internal joint pressures, which may lead to bulging, kinking or binding of the boot.
The IRD boot offers a smaller internal cross sectional area which reduces grease fill in the joint and allows for high speed rotation typically needed for torque transfer applications. However, the IRD boot requires an extension cover extending from the outer joint part. This extension cover may interfere with the angular rotation of a CVJ forming a DTF connection. Also, the extension cover may interfere with the optimization of various parameters desired in a DTF connection, such as the parameters described in PCT Publication No.: WO 2007/044003 incorporated by reference herein. One solution to the IRD boot for sealing a DTF joint is to use a membrane seal. A membrane seal, however, is also sensitive to increased internal joint pressures that may lead to bulging, kinking, binding or tearing of the boot. Also, the membrane seal may limit the allowable angular rotation of a DTF joint.
It is desirable to have a grease shield sealing system for a DTF CVJ that overcomes the limitations indicated above. It is also desirable to provide a sealing system suitable for high-speed constant velocity joint applications.